Motorcycle aerodynamics, a slippery and windy, slope?

[PeterS]

Why ? All you want is the power and these engines are basically industrial.

[renault_megane_dci]

if your engine does not spin, you need wide ratio gears or a lot of gears.
I assume wide ratio because it is the cheapest.
If so, you gonna lock the rear tire at the ease of the throttle

[PeterS]

I'm interested in the power band and the torque band, the speed at which they are generated is irrelevant. I've driven bikes and cars that ran at very low revs but with acceptably power and torque that were very good to drive or ride.

[Grant-53]

The next item is to find a transmission. Since the torque curve on these is quite flat the steps between ratios can be greater than a sport bike. A range of 12 or 14 speeds might be nice with progressions of 15%. Much depends on vehicle weight and drag. Some folks design down from a motorcycle with a steel frame. I would be looking at designing up from an aluminum bike making the components only as heavy as needed. Around here 85 mph is all the speed we can use.

[PeterS]

12 or 14 speeds? That's expecting a very narrow power band but the easiest way might be 2 x4 speed bike boxes in series ...messy though .

[Frank Lee]

A bike you need to shift like a semi-tractor? LOL

[Grant-53]

Right. Shifting becomes like a triple crank mountain bike or a 4wd truck.

[sendler]

Here is one of the few articles I have ever found with values for measured coefficient of drag of motorcycles with riders.
.
Sport Rider-Testing Suzuki Hayabusa and Kawasaki ZX-12R aerodynamics in the wind tunnel
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[PeterS]

Thanks Sendler , bookmarked !

[Grant-53]

A typical set up for the mountain bikes is triple front gears and 6-8 rear gears.
A 3 speed box in series with a 6 speed gearbox is comparable. The 50cc racing Kreidler motorcycles had a 15 speed system. With that many ratios available, cyclists often tape a gear chart to the handlebars to remember the best shifting sequence. Gear ratios are plotted on natural log graph paper and the spacing analyzed. An ideal set up has equal spacing and no duplicate ratios. At 16 to 20 hp, enough power is generated for brisk acceleration of a Last Vetter equipped motorcycle weighing 350 lbs.